The present invention relates to clutch mechanisms for use in vehicle seats and force transmission mechanisms having such clutch mechanisms. More particularly, the present invention relates to clutch mechanisms that are constructed to function when external forces are applied thereto via force input cables (e.g., when seat backs of the seats are pressed rearwardly by backs of passengers sitting on the vehicle seats), thereby selectively transmitting the external forces to force output cables disposed in the seats as pulling forces, and force transmission mechanisms having such clutch mechanisms.
A clutch mechanism for use in a vehicle seat that is constructed to function when an external force is applied thereto is already known. Such a clutch mechanism is taught, for example, by German Patent Number 10232017.
This clutch mechanism is constructed to function when an external load or force is applied thereto (e.g., when a seat back of the seat is pressed rearwardly by a back of a passenger sitting on the seat), thereby transmitting the force to a lock mechanism of a head rest. Upon transmission of the force to the lock mechanism, the lock mechanism is changed to an unlocking condition, so that the head rest can be tilted forwardly. Further, this clutch mechanism is constructed to function only when the force is applied quickly.
The known clutch mechanism is constructed to be pneumatically actuated when the force is applied quickly thereto. Therefore, the clutch mechanism may not properly function depending on an ambient temperature even if the force is applied quickly. In addition, the pneumatically actuated clutch mechanism may have a complicated structure. This may lead to an increased manufacturing cost of the clutch mechanism.